Tunnel provisioning with link aggregation

ABSTRACT

A method for processing data packets in a communication network includes establishing a path for a flow of the data packets through the communication network. At a node along the path having a plurality of aggregated ports, a port is selected from among the plurality to serve as part of the path. A label is chosen responsively to the selected port. The label is attached to the data packets in the flow at a point on the path upstream from the node. Upon receiving the data packets at the node, the data packets are switched through the selected port responsively to the label.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to co-pendingU.S. non-provisional patent application entitled “Tunnel ProvisioningWith Link Aggregation,” having U.S. Ser. No. 15/679,179, filed Aug. 17,2017, which is a continuation of, and claims priority to, U.S. Ser. No.15/415,933, filed Jan. 26, 2017 2015 (U.S. Pat. No. 9,749,228, issuedAug. 29, 2017), which is a continuation of, and claims priority to, U.S.Ser. No. 14/834,480, filed Aug. 25, 2015 (U.S. Pat. No. 9,590,899,issued Mar. 7, 2017), which is a continuation of, and claims priorityto, U.S. Ser. No. 13/969,520, filed Aug. 17, 2013 (U.S. Pat. No.9,118,602, issued Aug. 25, 2015), which is a continuation of, and claimspriority to, U.S. Ser. No. 13/116,696, filed May 26, 2011 (U.S. Pat. No.8,837,682, issued Sep. 17, 2013), which is a continuation of, and claimspriority to, U.S. Ser. No. 11/123,801, filed May 6, 2005 (U.S. Pat. No.7,974,202, issued Jul. 5, 2011), each of which are hereby incorporatedby reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to communication networks, andparticularly to methods and systems for performing link aggregation intunneled networks.

BACKGROUND OF THE INVENTION

Multiprotocol Label Switching

Multiprotocol Label Switching (MPLS) has gained popularity as a methodfor efficient transportation of data packets over connectionlessnetworks, such as Internet Protocol (IP) networks. MPLS is described indetail by Rosen et al., in Request for Comments (RFC) 3031 of theInternet Engineering Task Force (IETF), entitled “Multiprotocol LabelSwitching Architecture” (January, 2001), which is incorporated herein byreference. This RFC, as well as other IETF RFCs cited herein below, isavailable at www.ietf.org/rfc.

In MPLS, each packet is assigned to a Forwarding Equivalence Class (FEC)when it enters the network, depending on its destination address. Thepacket receives a fixed-length label, referred to as an “MPLS label”identifying the FEC to which it belongs. All packets in a given FEC arepassed through the network over the same path by label-switching routers(LSRs). The flow of packets along a label-switched path (LSP) under MPLSis completely specified by the label applied at the ingress node of thepath. Therefore, an LSP can be viewed as a tunnel through the network.

MPLS defines a label distribution protocol (LDP) by which one LSRinforms another of the meaning of labels used to forward traffic betweenand through them. Another example is RSVP-TE, which is described byAwduche et al., in IETF RFC 3209 entitled “RSVP-TE: Extensions to RSVPfor LSP Tunnels” (December, 2001), which is incorporated herein byreference. RSVP-TE extends the well-known Resource Reservation Protocol(RSVP), allowing the establishment of explicitly-routed LSPs using RSVPas a signaling protocol. RSVP itself is described by Braden et al., inIETF RFC 2205, entitled “Resource ReSerVation Protocol (RSVP)—Version 1Functional Specification” (September, 1997), which is incorporatedherein by reference.

Section 1 Of RFC 2205 defines an “admission control” decision module,which is used during reservation setup to determine whether a node hassufficient available resources to supply the requested quality ofservice. The admission control module is used in RSVP-TE for setting upMPLS tunnels.

U.S. Patent Application Publication US 2002/0110087 A1, entitled“Efficient Setup of Label-Switched Connections,” whose disclosure isincorporated herein by reference, describes methods and systems forcarrying layer 2 services, such as Ethernet frames, throughlabel-switched network tunnels.

Ethernet Link Aggregation

Link aggregation (LAG) is a technique by which a group of parallelphysical links between two endpoints in a data network can be joinedtogether into a single logical link (referred to as a “LAG group”).Traffic transmitted between the endpoints is distributed among thephysical links in a manner that is transparent to the clients that sendand receive the traffic. For Ethernet networks, link aggregation isdefined by Clause 43 of IEEE Standard 802.3ad, Carrier Sense MultipleAccess with Collision Detection (CSMA/CD) Access Method and PhysicalLayer Specifications (2002 Edition), which is incorporated herein byreference. Clause 43 defines a link aggregation protocol sub-layer,which interfaces between the standard. Media Access Control (MAC) layerfunctions of the physical links in a link aggregation group and the MACclients that transmit and receive traffic over the aggregated links.

U.S. Patent Application Publication US 2004/0228278 A1, entitled“Bandwidth Allocation for link Aggregation,” the disclosure of which isincorporated herein by reference, describes methods for bandwidthallocation in a link aggregation system. The methods described in thispublication are meant to ensure that sufficient bandwidth will beavailable on the links in the group in order to meet service guarantees,notwithstanding load fluctuations and link failures.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide tunnel provisioning withlink aggregation. Briefly described, a first aspect of the presentinvention is directed to a method for assigning and utilizing anEthernet physical, data port in an Ethernet Link Aggregation Group (LAG)in a Multi-Protocol Label Switching (MPLS) network. The method includesthe steps of selecting, by a first MPLS/LAG switch, from a plurality ofphysical data ports in said first MPLS LAG switch, a single physicaltunnel port which meets a bandwidth requirement of a network tunnel,wherein said single physical tunnel port has a port serial number,assigning, by said first MPLS/LAG switch, said single physical tunnelport to said network tunnel, preparing, by said first MPLS/LAG switch, adata packet label by which said single physical tunnel port may beidentified, receiving, by said first MPLS LAG switch, a data packetincluding said data packet label at said first MPLS/LAG switch, andswitching, by said first MPLS LAG switch, said data packet to saidsingle physical tunnel port according to said serial port number, andsending said data packet to a second MPLS/LAG switch via said singlephysical tunnel port.

A second aspect of the present invention includes a method for tagging apacket for transport through an Ethernet physical data port in anEthernet Link Aggregation Group (LAG) located downstream from apreceding node in a Multi-Protocol Label Switching (MPLS) network tunnelemploying Resource Reservation Protocol Traffic Engineering (RSVP-TE)tunnel provisioning. The method includes the steps of sending downstreamto a MPLS/LAG switch, by the preceding node, an RSVP-TE PATH message,the RSVP-TE PATH message including a LABEL_REQUEST object requesting anetwork tunnel, and a bandwidth requirement, receiving, by the precedingnode, a packet label sent by the MPLS/LAG switch, said packet labelincluding a serial number of a single physical tunnel port in the MPLSLAG switch, and wherein the single physical tunnel port meets thebandwidth requirement, attaching by the preceding node, said data packetlabel to a data packet sent by the preceding node, wherein the datapacket is intended to be forwarded via the single physical tunnel port,and sending downstream to the MPLS/LAG switch, by the preceding node, adata packet including said data packet label.

A third aspect of the present invention includes an apparatus forassigning and utilizing an Ethernet physical data port in an EthernetLink Aggregation Group (LAG) located downstream from a preceding node ina Multi-Protocol Label Switching (MPLS) network tunnel employingResource Reservation Protocol Traffic Engineering (RSVP-TE) tunnelprovisioning, the LAG having a first MPLS/LAG switch and a secondMPLS/LAG switch. The apparatus includes a processor, which is configuredto receive a tunnel configuration request message from the precedingnode make a selection from a plurality of physical data ports in saidfirst MPLS/LAG switch, of a single physical tunnel port which meets abandwidth requirement of the network tunnel, wherein said singlephysical tunnel port has a port serial number, assign said singlephysical tunnel port to the network tunnel, prepare a data packet label,by which said single physical tunnel port may be identified, dedicate asub-set of bits of said data packet label to encode said port serialnumber of said single physical tunnel port, and publish said packetlabel upstream.

The apparatus includes a mapper configured to receive a data packet froman upstream node, detect said data packet label in said data packet, andif said data packet contains said data packet label, to direct the firstMPLS/LAG switch to switch said data packet to said single physicaltunnel port, and send said data packet to the second MPLS/LAG switch viasaid single physical tunnel port.

Other systems, methods and features of the present invention will be orbecome apparent to one having ordinary skill in the art upon examiningthe following drawings and detailed description. It is intended that allsuch additional systems, methods, and features be included in thisdescription, be within the scope of the present invention and protectedby the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram that schematically illustrates an MPLScommunication network, in accordance with an embodiment of the presentinvention;

FIG. 1B is a block diagram that schematically illustrates an MPLS/LAGswitch, in accordance with an embodiment of the present invention;

FIG. 2 is a block diagram that schematically illustrates anencapsulated. MPLS packet, in accordance with an embodiment of thepresent invention;

FIG. 3 is a flow chart that schematically illustrates a method for portallocation, in accordance with an embodiment of the present invention;and

FIG. 4 is a flow chart that schematically illustrates a method for portallocation, in accordance with another embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1A is a block diagram that schematically illustrates a computercommunication network 20, in accordance with an embodiment of thepresent invention. System 20 includes two MPLS networks 22, labeled Aand B, i.e., networks containing MPLS-capable switches. (Typically,these networks may also carry non-MPLS traffic, as in MPLS-capable IPnetworks that are known in the art.) MPLS networks A and B are connectedvia MPLS/LAG switches 26, using N physical Ethernet ports 24. Ports 24are aggregated into a LAG group 25 using link aggregation (LAG) methodsdefined in the IEEE 802.3ad specification cited above. The two MPLS/LAGswitches 26, which also function as LSRs, perform link aggregation andother packet routing/switching functions, according to methods whichwill be described below.

An MPLS tunnel 28 (a label switched path, or LSP, according to the MPLSspecification cited above) s established from an ingress node in MPLSnetwork A, through the two switches and the LAG group, to an egress nodein MPLS network B. (The ingress and egress nodes are not shown in thefigure.) The tunnel forms a path over which data frames traverse fromthe ingress node to the egress node. In the exemplary configuration ofFIG. 1A, the MPLS tunnel is switched through one of ports 24, labeled“PORT 3.” The term “downstream” typically denotes the direction ofpacket flow from the ingress node to the egress node along the tunnel.The term “upstream” denotes the opposite direction. The term “hop”denotes a part of the tunnel that connects two consecutive LSRs.

As part of the MPLS tunnel provisioning process (which is described inRFC 3031) each LSR along tunnel 28 attaches an MPLS label to the packetsit transmits downstream to the next LSR, identifying the packets thatbelong to tunnel 28. Thus, in the example shown in FIG. 1A, MPLS/LAGswitch A receives packets to which MPLS labels have been attached at apreceding node 29, which is an LSR located in MPLS network A, upstreamfrom MPLS/LAG switch A. In most MPLS implementations, a given MPLS labelis used within a single hop along the tunnel. In this case node 29 isthe LSR that immediately precedes MPLS/LAG switch A in tunnel 28. Inother MPLS implementations, the same label may be used for severaladjacent hops of the tunnel, so that there may be one or more additionalLSRs located between node 29 and switch A.

The exemplary network configuration shown in FIG. 1A was chosen for thesake of conceptual clarity. Other tunneled network configurations withlink aggregation may use the methods and systems disclosed herein, aswill be apparent to those skilled in the art. As noted earlier, theseconfigurations may use MPLS and Ethernet LAG or other tunneling and linkaggregation protocols known in the art.

FIG. 1B is a block diagram that schematically shows details of MPLS/LAGswitch 26, in accordance with an embodiment of the present invention. Onthe transmitting side of the LAG group, the switch typically receives anMPLS payload, encapsulated in Ethernet frames from the ingress node(either directly or via other LSRs in MPLS network A). Switch 26switches the MPLS payload according to the MPLS label andre-encapsulates the MPLS payload into an Ethernet frame destined to theLAG group. Following the MPLS switching process, the MPLS switchperforms the LAG function and maps the Ethernet frame to one of thephysical Ethernet ports 24 of LAG group 25. On the receiving side of theLAG group, the switch collects the Ethernet frames from the ports of LAGgroup 25 and sends them to the egress node (either directly or via otherLSRs, as defined by the tunnel).

Switch 26 has an RSVP-TE processor 30 and a CAC (Connection AdmissionControl) processor 32, which handle MPLS tunnel provisioning and theassociated signaling. Although processors 30 and 32 are shown, for thesake of conceptual clarity, as separate functional units, in practicethese two functions are typically implemented as software processes onthe same (processor. Practically speaking, they may generally beregarded as a single processor, regardless of implementation. Switch 26also has a mapper 34, which maps each MPLS payload to a specificphysical Ethernet port 24 (following the payload encapsulation into anEthernet frame), according to methods which will be described below.

The methods described herein typically address a unidirectional packetflow, i.e., packets flowing from MPLS network A to MPLS network B. Themethods are presented in this way because MPLS tunnels areunidirectional by definition. This fact does not limit the disclosedmethods in any way to unidirectional message flows. Bidirectional packetflow is typically implemented by setting up two separate, independentMPLS tunnels.

MPLS/LAG switch 26 may be implemented using a network processor, whichis programmed in software to carry out the functions described hereinand is coupled to suitable hardware for interfacing with the MPLSnetwork and Ethernet ports. Switch 26 may either include a standaloneunit or may alternatively be integrated with other computing functionsof the network processor. Some or all of the functions of switch 26 canalso be implemented using a suitable general-purpose computer, aprogrammable logic device, an application-specific integrated circuit(ASIC) or a combination of such elements.

FIG. 2 is a block diagram that schematically illustrates an MPLS packetencapsulated into an Ethernet II format, in accordance with anembodiment of the present invention. The Ethernet frame includes a MAC(Media Access Control) destination address field 40, a MAC sourceaddress field 42, and an Ethertype identifier field 46 used to identifythe specific protocol. The frame ends with a frame check sequence (FCS)field 48 used for error detection. The encapsulated MPLS packet includean MPLS header 50, which has an MPLS label field 52. An MPLS payloadfield 54 includes the message body, containing information transmittedby the MPLS packet. In some implementations, the frame also includesoptional VLAN Ethertype and VLAN tag fields.

Mapper 34 of switch 26 performs a trapping function that usesinformation carried in one or more fields of the encapsulated MPLSpacket to select the physical Ethernet port for mapping the packet. TheIEEE 802.3ad standard cited above does not dictate any particularmapping method for link aggregation, other than forbidding frameduplication and requiring that frame ordering be maintained over allframes in a given flow. In practice, to meet these requirements, themapper typically maps all frames in a given MPLS tunnel to the samephysical port.

The mapping function typically uses MPLS label 52 for mapping, since theMPLS label uniquely identifies MPLS tunnel 28, and it is required thatall MPLS packets belonging to the same tunnel be switched through thesame physical port 24. Additionally or alternatively, the mappingfunction uses a “PW” label (pseudo wire label, formerly known as avirtual connection, or VC label), which is optionally added to MPLSheader 50. The PW label includes information that the egress noderequires for delivering the packet to its destination, and is optionallyadded during the encapsulation of MPLS packets. Additional detailsregarding the VC label can be found in an IETF draft by Martini et al.entitled “Encapsulation Methods for Transport of Ethernet Frames OverMPLS Networks” (IETF draft-ietf-pwe3-ethernet-encap-07.txt, May, 2004),which is incorporated herein by reference. In some embodiments, mapper34 applies a hashing function to the MPLS and/or PW label, as will bedescribed below.

Port Coding

FIG. 3 is a flow chart that schematically illustrates a method for portallocation using port coding, in accordance with an embodiment of thepresent invention. This method, as well as the method of FIG. 4described below, is used to provision MPLS tunnel 28 by allocatingbandwidth on one of the physical ports of LAG group 25.

The method of FIG. 3 begins when the preceding node asks to establish apart of tunnel 28 (having one or more hops) for sending MPLS packets toMPLS/LAG switch 26 A. The preceding node requests and then receives theMPLS label, which it will subsequently attach to all packets that aresent to MPLS/LAG switch 26 labeled A. The preceding node sendsdownstream an RSVP-TE PATH message augmented with a LABEL_REQUESTobject, as defined by RSVP-TE, to MPLS/LAG switch A, at a labelrequesting step 60. The PATH message typically includes informationregarding service properties that are requested for tunnel 28. Theservice properties may include a guaranteed bandwidth (sometimes denotedCIR—Committed Information Rate) and a peak bandwidth (sometimes denotedPIR—Peak Information Rate), as well as a requested CoS (Class ofService—a measure of packet priority).

CAC processor 32 of switch A receives the PATH message and extracts therequested service properties. The CAC processor examines the availablebandwidth of all ports 24 in LAG group 25 and selects a single physicalport (“the selected physical port”) on which to allocate bandwidth forMPLS tunnel 28, responsively to the requested service properties, at aport selection step 62. The selected physical port should be capable ofproviding sufficient peak and average bandwidths, as requested by thepreceding node (and, originally, by the ingress node).

In one embodiment the CAC processor selects the physical port having amaximum available bandwidth out of the ports of LAG group 25. Thisapproach attempts to distribute the packet flows evenly among thephysical ports. In an alternative embodiment, the CAC processor mayfollow a “first-to-fill” strategy, i.e., select a physical port thatwill reach the highest utilization after allocating the requestedbandwidth to tunnel 28. Any other suitable selection criteria may beapplied by CAC processor 32. In the event that none of physical ports 24has sufficient available bandwidth to comply with the requested serviceproperties, the CAC processor returns an error message to the precedingnode and denies the provisioning of tunnel 28. After successfullyselecting the physical port, the CAC processor allocates and reservesthe requested bandwidth for tunnel 28.

Regardless of the selection criterion used, the results of step 62 arethat (1) a single physical port is explicitly selected and assigned toMPLS tunnel 28, and (2) sufficient bandwidth is allocated to tunnel 28,considering only the available bandwidth of the selected physical port,rather than the total available bandwidth of LAG group 25. All packetsbelonging to tunnel 28 will be switched through the same selectedphysical port, using the port coding technique described herein below.

Having selected a physical port, RSVP-TE processor 30 of switch A nowgenerates a suitable MPLS label, at a label generation step 64. Thepreceding node upstream of switch A will subsequently attach this MPLSlabel to all MILS packets transmitted through tunnel 28 to switch A. Thelabel is assigned, in conjunction with the mapping function of mapper34, so as to ensure that all MPLS packets carrying this label areswitched through the physical port that was selected for this tunnel atstep 62. For this purpose, RSVP-TE processor 30 of switch A dedicates asub-set of the bits of MPLS label 52 to encode the serial number of theselected physical port. For example, the four least-significant bits ofMPLS label 52 may be used for encoding the selected port number. Thisconfiguration is suitable for representing LAG groups having up to 16physical ports (N<16). The remaining bits of MPLS label 52 may be chosenat random or using any suitable method known in the art.

RSVP-TE processor of switch 26 sends the generated MPLS label upstreamto the preceding node, using an RSVP-TE RESV message augmented with aLABEL object, at a label sending step 66. At this stage, the part oftunnel 28 between the preceding node and switch A is provisioned andready for use. The preceding node attaches the aforementioned MPLS labelto all subsequent MPLS packets that it sends downstream through tunnel28 to MPLS/LAG switch A, at a packet sending step 68.

Mapper 34 of switch A maps the received packets belonging to tunnel 28to the selected physical Ethernet port at a mapping step 70. For thispurpose, mapper 34 extracts the MPLS label from each received packet anddecodes the selected physical port number from the dedicated sub-set ofbits, such as the four LSB, as described in step 64 above. The decodedvalue is used for mapping the packet to the selected physical port,which was allocated by the CAC processor at step 62 above. In thefour-bit example described above, the mapping function may be writtenexplicitly as: Selected port number=((MPLS label) and (0x0000F)),wherein “and” denotes the “bitwise and” operator.

In an alternative embodiment, RSVP-TE processor 30 generates anarbitrary MPLS label at step 64 and stores this label together with thecorresponding serial number of the selected physical port n a lookuptable or other data structure. At step 70, the mapper extracts the MPLSlabel from each received MPLS packet and queries the lookup table withthe MPLS label value to determine the physical port through which toswitch the packet.

Inverse Hashing

FIG. 4 is a flow chart that schematically illustrates an alternativemethod for port allocation, in accordance with another embodiment of thepresent invention. Similar to the method shown in FIG. 3 above, themethod begins with the preceding node in MPLS network A asking toestablish a part of MPLS tunnel 28 for sending MPLS packets to switch A.The preceding node sends downstream an RSVP-TE PATH message, at a labelrequesting step 80, which is identical to label requesting step 60 ofFIG. 3 above. CAC processor 32 of switch A receives the PATH message,extracts the requested service properties, and selects a physical portout of group 25, at a port selection step 82. Step 82 is identical toport selection step 62 of FIG. 3 above.

In this method, the mapping function used by mapper 34 of switch A is ahashing function. Various hashing functions are known in the art, andany suitable hashing function may be used in mapper 34. Since thehashing operation is performed for each packet, it is desirable to havea hashing function that is computationally simple.

As mentioned above, the hashing function typically hashes the value ofMPLS label. 52 to determine the selected physical port, as the MPLSlabel uniquely identifies tunnel 28. For example, the following hashingfunction may be used by mapper 34: Selected port number=1+((MPLS label)mod N), wherein N denotes the number of physical Ethernet ports in LAGgroup 25, and “mod” denotes the modulus operator. Assuming the values ofMPLS labels are distributed uniformly over a certain range, thisfunction achieves a uniform distribution of port allocations for thedifferent MPLS labels. It can also be seen that all packets carrying thesame MPLS label (in other words—belonging to the same MPLS tunnel) willbe mapped to the same physical port.

Returning to the description of FIG. 4, RSVP-TE processor 30 of switch Atakes the serial number of the selected physical port (selected at step82) and generates MPLS label 52 by calculating an inverse of the hashingfunction, at an inverse calculation step 84. The purpose of this step isto choose an MPLS label in a way that would cause the hashing functionof mapper 34 to output the selected physical port (so that allsubsequent packets carrying this label will be switched through thisport). The following numerical example, which uses the hashing functiongiven above, demonstrates the inverse hashing process:

-   -   The inverse of the hashing function given above is: MPLS        label=(Selected port number−1)+N*MPLS.sub.p, wherein N denotes        the number of physical ports in group 25, and MPLS.sub.p denotes        a predetermined number, which is assigned by RSVP-TE processor        30 for each MPLS tunnel. Note that the value of MPLS.sub.p does        not affect the hashing function, since different values of        MPLS.sub.p only add integer multiples of N to the value of the        MPLS label. The modulus operator of the hashing function        eliminates this effect. This mechanism enables the same        hashing/inverse-hashing functions to generate multiple MPLS        labels to support multiple tunnels.    -   Assume that MPLS.sub.p=21882. Assume also that the LAG group has        3 ports (N=3) and that the CAC processor has selected physical        port number 2 at step 82. The MPLS label calculated by the        RSVP-TE processor at step 84 is thus given by: MPLS        label=(2−1)+3*21882=65647

Having generated the MPLS label, RSVP-TE processor of switch A sends theMPLS label upstream to the preceding node, at a label sending step 86,which is identical to label sending step 66 of FIG. 3 above. At thisstage, the part of tunnel 28 between the preceding node and switch A isprovisioned and ready for use. The preceding node attaches theaforementioned MPLS label to all subsequent MPLS packets, belonging totunnel 28, that are sent downstream to MPLS/LAG switch A, at a packetsending step 88.

Mapper 34 of switch A maps each received packet to the selected physicalport of LAG group 25 using the hashing function, at a hashing step 90.Mapper 34 extracts the MPLS label from each received packet and uses thehashing function to calculate the serial number of the selected physicalport, which was selected by the CAC processor at step 82. Following thenumerical example given above, the mapper extracts MPLS label=65647 fromthe packet. Substituting this value and N=3 into the hashing functiongives: Selected port number=1+(65647 mod 3)=2, which is indeed the portnumber selected in the example above.

Lag Protection

The IEEE 802.3ad standard cited above describes a protection mechanismfor cases in which one of ports 24 fails or is intentionally taken outof service for any reason. In this case, the mapping function shoulddistribute the data packets among the remaining ports. When using linkaggregation in conjunction with tunneling methods such as MPLS, allpackets belonging to a given tunnel should be switched through a singleport 24. This property should be maintained in case of failure or portreconfiguration.

In an embodiment of the present invention, one of the N ports 24 of LAGgroup 25 is not used under normal network conditions and is maintainedas a backup port. In the event that one of the active N−1 ports 24 failsor is taken out of service, switch A replaces the failed port with thebackup port. As all ports 24 typically have equal bandwidths, theservice properties required by tunnel 28 can be maintained.

In one embodiment, switch A may revert to the original port as soon asit recovers or returned into service. In an alternative embodiment, oncethe backup port has replaced a failed port, it continues to function asan ordinary port. The failed port, once recovered, begins to function asa backup port.

Although the methods and systems described hereinabove address mainlyMPLS and Ethernet link aggregation, the principles of the presentinvention may also be used in conjunction with other communicationprotocols. For example, the methods described above may be adapted fixuse with other types of labeled traffic flows, such as flows labeled inaccordance with other tunneling methods, and other link aggregationmethods.

It will thus be appreciated that the embodiments described above arecited by way of example, and that the present invention is not limitedto what has been particularly shown and described hereinabove. Rather,the scope of the present invention includes both combinations andsub-combinations of the various features described hereinabove, as wellas variations and modifications thereof which would occur to personsskilled in the art upon reading the foregoing description and which arenot disclosed in the prior art.

The invention claimed is:
 1. A method performed by an Ethernet switchthat comprises multiple physical ports cooperating as an Ethernet LinkAggregation Group (LAG) and a first Ethernet port, the methodcomprising: assigning a distinct number to each port of the multiplephysical ports; receiving, by the switch via the first Ethernet port,multiple messages, each of the messages comprises a frame or packet thatcomprises a source address field, a destination address field, and afirst value carried in a first field other than the source ordestination addresses fields; applying a hash function to each of thevalues in the first field of each of the received multiple messages;selecting, by the switch, a first port from the multiple physical portsin response to the first value; and sending, by the switch, each of thereceived multiple messages via the selected first port, wherein the hashfunction maps a respective assigned port number to each one of thevalues in the first field, and wherein the selecting comprises selectingthe port that is assigned the result of the hash function of therespective message.
 2. The method according to claim 1, wherein the LAGis according to, based on, or compatible with, Clause 43 of IEEEStandard 802.3ad, 2002 Edition.
 3. The method according to claim 1, foruse with a plurality of messages, each of the plurality of messagesincludes an MPLS label, wherein the Ethernet switch further comprises aLabel-Switching Router (LSR) according to Multiprotocol Label Switching(MPLS) protocol, and wherein the method further comprising routing thereceived plurality of messages according to their MPLS label.
 4. Themethod according to claim 1, wherein the Ethernet switch furthercomprises a Label-Switching Router (LSR) according to MultiprotocolLabel Switching (MPLS) protocol, and wherein the first field comprisesan MPLS label field.
 5. The method according to claim 4, furthercomprising encapsulating or decapsulating the value in the MPLS labelfield.
 6. The method according to claim 1, wherein the first fieldcomprises a Pseudo Wire (PW) label or a Virtual Connection (VC) labelfield.
 7. The method according to claim 1, wherein the first fieldcomprises a Virtual Local Area network (VLAN) Ethertype or a VLAN tag.8. The method according to claim 1, wherein the switch comprises Nmultiple physical ports, and wherein the hash function comprises aModulo N function.
 9. The method according to claim 1, wherein the hashfunction comprises, uses, or is based on, 1+((indicator value) mod (N)),wherein the ‘mod’ is the modulo operator.
 10. The method according toclaim 1, further comprising defining a tunnel via the switch thatincludes the selected port, and wherein the multiple messages arecarried over the tunnel.
 11. The method according to claim 10, whereinthe tunnel is unidirectional or bidirectional.
 12. The method accordingto claim 10, wherein the selecting comprises selecting a port having aminimum available bandwidth among the multiple physical ports, which isnot less than a bandwidth requirement of the tunnel.
 13. The methodaccording to claim 1, further comprising inserting into the first fielda set of bits that identify the selected first port.
 14. The methodaccording to claim 1, wherein each of the source and destinationaddresses is a Media Access Control (MAC) address.
 15. The method ofclaim 1, further comprising the step of receiving, by the switch via thefirst Ethernet port, a request message that comprises a data packetlabel associated with a network tunnel for configuration of the networktunnel.
 16. The method of claim 15, wherein the request message isreceived from a preceding MPLS/LAG switch.
 17. The method of claim 15,wherein the request message comprises an RSVP-TE PATH message augmentedwith a LABEL_REQUEST object.
 18. The method according to claim 17,wherein the request message comprises an indication of a serviceproperty, and wherein the selecting of the selected port comprisesidentifying a physical port in compliance with the service property. 19.The method according to claim 18, wherein the service property comprisesat least one of: a guaranteed bandwidth; a peak bandwidth; and a classof service.
 20. The method according to claim 1, wherein the selectingis further based on selecting a port having a maximum availablebandwidth among the multiple physical ports.
 21. The method according toclaim 1, further comprising protecting against a failure or againsttaking out of service, of a port of the multiple physical ports.
 22. Themethod according to claim 21, wherein the protection is a revertiveprotection.
 23. The method according to claim 1, further comprising:detecting a failure or out-of-service state of the first selected port;selecting, by the switch, a second port from the multiple physical portsin response to the first value and to the detecting of the failure orout-of-service state; and sending, by the switch, each of the receivedmultiple messages via the selected second port.
 24. The method accordingto claim 23, further comprising: detecting a recovery from the failureor out-of-service state of the selected first port; selecting, by theswitch, the first port from the multiple physical ports in response tothe first value and to the detecting of the recovery; and sending, bythe switch, each of the received multiple messages via the selectedfirst port.
 25. The method according to claim 23, further comprisingdefining, by the switch, a backup port distinct from the selected portfrom the multiple physical ports, and wherein the selected second portis the backup port.
 26. The method according to claim 1, wherein allports of the LAG have equal bandwidth.
 27. The method according to claim1, for use with an additional Ethernet switch, wherein the methodfurther comprising preparing the multiple messages by the additionalEthernet switch; and sending the multiple messages by the additionalEthernet switch via the first Ethernet port.
 28. The method according toclaim 27, wherein the preparing comprises calculating and inserting thevalue in the first field of each of the multiple messages.
 29. Themethod according to claim 28, wherein the calculating of the valueprovides for the selecting, by the Ethernet switch, the first selectedport from the multiple physical ports.
 30. The method according to claim1, wherein the received multiple messages are sent in the same order oftheir receiving by the switch.
 31. The method according to claim 1, foruse with multiple possible values in the first field, and for use with amemory in the switch that stores an association of a single port out ofthe multiple physical ports to each of the possible values, wherein theselection is based on using the memory.
 32. The method according toclaim 31, further comprising storing, by the switch, the association.33. The method according to claim 1, wherein the switch is a stand-aloneunit that comprises a software and a network processor for executing thesoftware.